Pneumatic device for automatic control system of sliver{40 s thickness

ABSTRACT

In the automatic control system of sliver&#39;&#39;s thickness wherein the thickness of sliver continuously delivered from a draft mechanism is measured by an air-micrometer and, when a portion of sliver having unacceptable thickness is detected, the draft ratio is changed so as to produce sliver having allowable variation of thickness, the measuring device of the air-micrometer is provided with a trumpet-like condensing member and a delivery cylindrical member disposed at a coaxially downstream position so that a space for embracing the sliver in pressurized air is formed between both members.

United States Patent [1 1 g I Tooka 1 1 Jan. 16,1973

[54] PNEUMATIC DEVICE FOR AUTOMATIC CONTROL SYSTEM OF SLIVERKS THICKNESS [75] Inventor: Takuzo Tooka, Aichi-ken, Japan [73] Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho, Kariya-shi, Aichi-ken, Japan 22 Filed: Aug 2, 1971 21 App]. No.: 168,118

[30] Foreign Application Priority Data Aug.3, 1970 Japan ..45/68209 52 U.S.Cl ..19/240,73/37.7 [51] lnt.Cl. ..D0lh5/38 [58] FieldofSearch ..19/239,240,241,.32;

[56] References Cited UNITED STATES PATENTS 2,100,588 11 1937 Claus ..19/.32

3,088,175 5/1963 Aoki ..l9/240 Primary Examiner-Dorsey Newton Attorney-Robert E. Burns et al.

[5 7] ABSTRACT In the automatic control system of slivers thickness wherein the thickness of sliver continuously delivered from a draft mechanism is measured by an airmicrometer and, when a portion of sliver having unacceptable thickness is detected, the draft ratio is changed so as to produce sliver having allowable variation of thickness, the measuring device of the airmicrometer is provided with a trumpet-like condensing member and a delivery cylindrical member disposed at a coaxial ly downstream position so that a space for embracing the sliver in pressurized air is formed between both members.

4 Claims, 7 Drawing Figures PATENTEDJM is 1915 I 3,710,421

SHEEI10F4' PATENTEDJAH 16 1975 BACK PRESSURE Pl BACK PRESSURE (PI) in kg /cm in kg/cm SHEET 3 BF 4 Q 0 y 006 "I 0 V 0.05

I w 2 W5 I I THICKNESS OF SILVER (an I" f m THICKNESS 0F SlLVER (an) PNEUMATIC DEVICEFOR AUTOMATIC CONTROL SYSTEM OF SLIVER 'S THICKNESS SUMMARY OF THE INVENTIONS It is well-known that an automatic control system utilizing a pneumatic measuringdevice for detecting slivers thickness has been applied for controlling slivers thickness within a predetermined allowable range, in spinning processes, particularly in a drawing process. In this system, a continuously delivering sliver from a draft mechanism is led into, an air-micrometer nozzle of trumpetlike shape, and the back pressure of the air-micrometer is detected by a bellows so as to convert the pressure variation corresponding to the variation of slivers thickness into a deformation of the bellows, the deformation of the bellows is converted into a reciprocal motion of a flapper, a pneumatichydraulic servo-mechanism is actuated by the motion of the flapper so that a speed control device related to the draft mechanism is actuated and the draft ratio of the draft mechanism can be controlled.

However, to measure the variation of slivers thickness with high sensitivity, it is requiredto satisfy a particular relation between the diameter of an orifice disposed in a supply conduit connected to a measuring nozzle and the diameter of the delivery aperture of the measuring nozzleand further it is required to choose the diameter of the measuring nozzle in such a way that it is filled by the passing sliver, in other words, it is required to maintain the pneumatic pressure applied to the measuring nozzle at a restricted level.

According to our experience, even though the above-mentioned conditions are satisfied, there is a certain noise caused by variation of fiber arrangement in the sliver which can be created by condensingva fleece to form a sliver. If it is required to satisfy the above-mentioned pneumatic pressure, the fleece which is continuously delivered from a pair of delivery rollers of a draft mechanism, is subjected to intense condensing so that there is a certain possibility of disturbing the orientation of fibers in the fleece. This disorientation of fibers degrades the results of the control system. Therefore, this disorientation is one of the causes creating noise of the control system. In the conventional measuring system using an air-micrometer, the sliver including disoriented fibers is directly exposed to a compressed air current while passing through the air-micrometer nozzle so that noise is created. As the physical properties such as elasticity, stiffness of fibers, are generally affected by humidity, temperature of atmosphere, the above-mentioned noise seems to be affected by the atmospheric condition. Consequently, it is considered that one method for eliminating the effect of the above-mentioned noise is an elimination of the cause which is due to the undesirable effect of forming sliver by utilizing the conventional air-micrometer nozzle which is provided with a continuous sliver path directly connected to a conduit for feeding compressed air.

Principle object of the present invention is to provide an improved pneumatic measuring device applicable to the automatic control system of sliver-thickness, by which the above-mentioned noise can be prevented.

Further object of the present invention is to provide an automatic control apparatus for controlling slivers thickness provided with the measuring device according to the present invention.

LII

BRIEF EXPLANATION OFTHE DRAWINGS FIG. I is a schematic diagram showing an automatic control apparatus utilizing the measuring device according to the present invention,

FIG. 2A is a side sectional view of one example of the conventional measuring device,

FIG. 2B is a sectional view the measuring device,

- taken along a line 2B-.2B in FIG. 2A,

FIG, 3 is a side sectional view of the measuring device shown in FIG. 1,

'FIGS. 4A, 4B and 4C are explanatory diagrams showing relations between the pressure of supply air and the thickness of sliver in three different conditions defined by various diameters of delivery aperture of the measuring device and of the orifice disposed in the conduit connecting the measuring device with the source of compressed air, respectively.

DETAILED ILLUSTRATION OF THE INVENTION Before illustration of the detailed construction and characteristic function of the measuring device according to the present invention, an embodiment of the automatic control system. utilizing the measuring device of the present invention is first illustrated. Referring to FIG. 1, an automatic control apparatus is fitted to a drafting mechanism such as a dirawing frame which comprises a pair of front rollers la, lb and a group of drafting rollers which are represented by a reference numeral 2 and disposed at an upstream postion of the front rollers. A supplied sliver 3 is drafted while passing through these rollers, because each pair of downstream rollers are driven at a higher surface speed than each pair of upstream rollers. A fleece 4 having desired thickness is delivered from the front rollers 1a, 1b and is condensed so as to form a sliver by a condenser of the measuring device 5 and then the sliver is delivered from the delivery nozzle of the measuring device 5 by the take up action of a pair of callender rollers 6a, 6b and then delivered into a can via a coiler tube 7 of a coiler motion mechanism. The measuring device 5 is connected to a conduit 8 which is connected to a bellows 12a symmetrically arranged with another bellows 12b and connected to a branch conduit 9 which is off set from the main conduit 10. The main conduit 10 is connected to a compressed air supply source 13 via a reserve chamber 11 by which an air pressure supplied to the conduit 10 is automatically regulated to a constant pressure p,,. Further, the conduit 10 is connected to the bellows 12b and is provided with an adjustable orifice 16 engaged with a regulating knob 17. Both bellows 12a and 12b are connected by a connecting rod 14 and a flapper 15 is connected to the rod 14. A pair of orifices l8 and 19 are disposed in the conduit 10 and the branch conduit 9 respectively. Consequently, an

air-micrometer is constructed by the above-mentioned components, the measuring device 5, orifice 18, and the orifices 16 and 19. The flapper is caused to turn about a fulcrum 15a in accordance with the deformations of the bellows 12a, 12b. A pair of nozzles a, 20b are disposed in such a way that the free end portion of the flapper 15 is positioned so as to intervene the nozzles 20a and 20b. These nozzles 20a, 20b are connected to a compressed air supply source 21 by way of a conduit 22 and a reserve chamber 24. These nozzles 20a, 20b are connected to respective bellows 26a, 26b by way of respective conduits 25a, 25b. These nozzles 20a, 20b are provided with an adjustable orifices 20a, 20b respectively. The compressed air supplied from the supply source 21 isautomatically adjusted to a predetermined constant pressure by the reserve chamber 24. The nozzles 20a, 20b are provided with respective apertures 23a, 23b each having the same size of aperture. As mentioned above, a second airmicrometer is constructed by the components, nozzles 20a, 20b, that is, the orifices 20a, 20b, free'spaces between the aperture 23a and the flapper 15, between the aperture 23b and the flapper 15, and bellows 26a and 26b.

The bellows 26a and 26b are connected by a connecting rod 28a which is provided with a pair of pilot valves 28b and 28c. Therefore, even through the turning motion of the flapper 15 is very small, the deformation of the bellows 12a, 12b is amplified by the second air-micrometer. If, it is required to eliminate any possible mechanical disturbance caused by the above-mentioned flapper mechanism, the flapper 15 can be rigidly secured to the connecting rod 14 so as to be able to displace with the longitudinal motion of the rod 14. To further amplify the aforesaid deformation, a hydraulic amplifier is connected to the air-micrometer. This hydraulic amplifier comprises an oil tank 27 and a supply conduit 29 provided with a compressor 38 and a return conduit 30, a control chamber 31 which is connected to the respective conduits 29 and 30, and a piston 33 slidably disposed in a chamber 32 which is connected to the control chamber 31 by way of a pair of connecting conduits 35a and 35b disposed at symmetrical positions. The pilot valves 28b, 28c are rigidly mounted on the connecting rod 28a at a distance apart which is the same as that of the conduits 35a, 35b so that the two connecting apertures of the control chamber 31 can be closed when pilot valves 28b, 28c are positioned at their natural position. The conduits 35a, 35b are provided with respective adjustable orifices. The return conduit terminates in the tank 27. The piston 33 is provided with a piston rod 34 which slidably passes through side walls of the chamber 32 as shown in the drawing. A variable speed converter 40 is mounted on the automatic control apparatus which is used for regulating the surface speed of the drafting mechanism. The variable speed converter 40 comprises a first vari-pitch sheave 37 mounted on a shaft 42 and a second vari-pitch sheave 43 rigidly mounted on a driving shaft 44 and a belt 45 which transmits rotation from the driving sheave 43 to the vari-pitch sheave 37 so that the shaft 42 is capable of transmitting a variable speed to regulate the draft ratio of the drafting mechanism. To actuate the vari-pitch sheaves 37, 45, a pair of levers 36a and 36b are pivoted to a supporting frame 46 by respective pins 41a, 41b, and the lever 36a is connected to one side member of the vari-pitch sheaves 37, 43 so that each pitch of the vari-pitch sheaves 37, 43 can be changed in accordance with the turning motion of the lever 36a about the pin 41a while the lever 36b keeps the other sidemember of the vari-pitch sheaves I 37, 43 stationary. A free end of the lever 36b is connected to a guide shaft 47, while a free end of the lever 36a is connected to a collar 48 which is slidably mechanism is driven at constant speed by the some driving source as the shaft 44 and the front roller (bottom roller) 1b is driven by the shaft 42, the draft ratio between the front rollers 1a, 1b and the adjacent upstream rollers (top and bottom rollers) can be regulated by the transversal displacement of the piston rod 34 which responds to the variation of the slivers thickness reversibly.

In the conventional automatic control system, a measuring device having the construction shown in FIGS. 2A, 2B is utilized. To clarify the characteristic construction of the measuring device according to the present invention, the construction of the conventional measuring device is hereinafter briefly illustrated. The measuring device 50 comprises a trumpet-like sliverinlet 51 and a cylindrical delivery portion 52 so that a sliver passage 53 is formed. The cylindrical delivery portion 52 is provided with a plurality of air passages 56 which pass laterally through the delivery portion 52. Further the cylindrical delivery portion 52 of the device 50 is rigidly supported by a collar 54 which is provided with a hollow cylindrical space 55 and an air inlet tap 59. To prevent leakage of air through possible slit between the delivery portion 52 and the collar 54, a pair of synthetic rubber washers 57, 58 are disposed therebetween. The hollow cylindrical space 55 encircles the delivery portion 52 so that the sliver passage 53 of the delivery portion 52 is connected to the space 55 through the air passages 56. Consequently, compressed air can be supplied into the sliver passage 53 by way of the tap 59, space 55 and the ainpassages 56. Provided that the above-mentioned measuring device 50 is utilized in the automatic control system shown in FIG. 1, instead of the nozzle 5, the fleece 4 delivered from the front rollers 1a b is condensed to form a sliver by the trumpet-like sliver inlet 51 and then goes directly to the delivery portion 52 where the sliver is exposed to the compressed air. As already illustrated in the summary section of this specification, the fiber arrangement in the fleece 4 is possibly changed during sliver formation at the inlet 51 if the required condition in connection with the pneumatic pressure is satisfied. It is our experience that air permeability through a mass of textile fibers varies in accordance with the fiber arrangement therein. For example, even though the same sample of sliver is used for testing the MICRONAIRE READING (ASTM D 1448), the reading varies in accordance with the condition of insertion of the sample into the fiber compression chamber of the testing instrument.

Consequently, if the fiber arrangement in the fleece 4 is changed during the sliver formation, the output of the device 50 is affected by the noise due to the variation of the fiber arrangement during the sliver formation. In other words, to obtain precise results from the control system, it is required to expose the sliver to the compressed air after being' formed in a stable and uniform condition.

According to the present invention, the measuring device shown in FIG. 1 has a particular construction as shown in FIG. 3 in detail. That is, the measuring nozzle of the present invention comprises a trumpet-like funnel condenser 5a and a delivery cylindrical member 5b provided with an expanded hollow cylindrical space 5d, which encircles the downstream end portion of the condenser 5a, and a hollow sliver passage 5e which is formed at a downstream end portion thereof. The entrance portion of the condenser 5a is rigidly secured to the upper circular edge portion of the delivery cylindrical member b and the downstream end of the condenser 5a is arranged so as to form an intervened space 5c from the inlet tapered wall of the hollow sliver passage 5e. The delivery cylindrical member Sbis connected to a conduit 8 which supplies compressed air such that the sliver is exposed to the compressed air when the sliver passes through the intervened space 5c.

Therefore, the fleece 4 delivered from the front rollers 1a, lb is condensed into a sliver by the condenser 5a and then the sliver is led into the sliver passage 5e of the delivery member 5b by the take-up motion of the callender rollers 6a and 6b.

When the sliver passes through the intervened space 50, the sliver is exposed to the compressed air supplied from the conduit 8. Therefore, if the fleece 4 is formed into a sliver having sufficient compactness to pass into the sliver passage 5e without any further changes of fiber arrangement, the above-mentioned noise, which is one of the troubles in the conventional automatic control system, can be eliminated successfully. In the above-mentioned condition, the sliver delivered from the condenser 5a tends to expand only a little so that any substantial degrading effect upon the precision of detection can be prevented.

From our experimental test, it is preferably to provide the delivery aperture of the condenser 5a with a diameter (a smaller than the diameter (0,) of the aperture of the delivery member 5b, to attain the above-mentioned result.

It is also considered that any draft of the sliver, which substantially changes the fiber arrangement therein, during passage through the space 5c, must be prevented. Otherwise, noise is created in the output of the measuring nozzle 5 so that the precision of detection is degraded. From our experiment, if the distance (I) from the termination of the funnel portion of the condenser 5a to the nip point of the callender rollers 60, 6b exceeds a certain figure, for example, more than twice the mean length of fiber (ASTM D 1447), there is a strong possibility of sliver separation. However, there is a certain limitation in locating the measuring nozzle at a position adjacent to the callender rollers 6a, 6b. From our experience, it is necessary to locate the measuring device 5 at a distance from the rollers such that (l) is not more than twice the mean length of the fibers, more preferably that the distance (I) is about mm, but not smaller than 35 mm, to prevent the abovementioned trouble. This restriction of (I) also permits easy preparation of sliver for insertion into the measur ing device 5 so as to reach the nip point of the callender rollers 6a, 6b.

As already illustrated in the preamble portion of this specification, to enable the full sensitivity of the air micrometer to be attained, the relative diameter (a,) of the orifice 18 and the diameter (a of the delivery aperture of the delivery member 5b of the measuring device 5 must be considered. Further the proper pressure (P of the compressed air must be considered in connection with the relative diameters a a From results of experiment the pressure (P,,) is preferably chosen in a range between 0.050.1 kg/cm so that the compressed air can be supplied to the conduit 8 without expansion.

In an automatic control system utilizing the airmicrometer for controlling the: thickness of sliver delivered from a draft mechanism, it is common to use bellows having a spring constant less than I kg/mm. If a bellows having a spring constant of kg/mm and an effective area of 26.5 cm for receiving the pneumatic pressure is applied for use with the air-micrometer of the control system shown in FIG. I, the free end of the flapper 15 turns by 0.3 mm from a pressure change of 7.5 X 10" kg/cm. Therefore, it will be understood that the above-mentioned sensitivity of the bellows and the flapper is sufficient for use with the control system. On the other hand, it is preferable that the pneumatic pressure (P of the supplied compressed air and the back pressure (P in the space 5d of the measuring device are as small as possible, so as to prevent disorientation of fiber arrangement in the sliver. However, if the pressures (P,), (P,,) are so small that sufficiently large deformation of the bellows can not be obtained because of the resilient property of the bellows, very complex mechanism is required for amplifying the small deformation of the bellows. On the other hand, if the pneumatic pressure (P is large the back pressure (P is large, and consequently the possibility of disorientation of fiber arrangement in the sliver increases. Further, it is impossible to prevent the expansion of the supplied compressed air so that the air current in the measuring device becomes complex, and the complex air current provides the output of the measuring device 5 with so called noise. In the air-micrometer according to the present invention, the back pressure (P,) in the space 5d of the measuring device 5 and the diameter (a of the delivery aperture of the cylindrical delivery member 5b are chosen in relation to the pneumatic pressure (P of the compressed air supplied from the reserve chamber 11 and the diameter (a,) of the orifice 18 so as to improve the sensitivity of the air-micrometer without any of the troubles mentioned above.

Generally, the thickness of sliver produced by the conventional drawing frame is in a range between 25 g/m (200- 500 grain/6 yards). To find the preferable relationship between the above-mentioned factors (P (P (0,) and (a,), for controlling the thickness of sliver which varies in the above-mentioned range, several experiments with theoretical analyses have been carried out.

Provided that the pneumatic pressure (P,,) is in a range low enough for the air to be considered as a noncompressible gas, the theoretical relation between (P and (P,,) can be represented by the following equation Where, a represents the total of the remaining spaces formed in the delivery aperture 5e when a sliver having a thickness W passes therethrough.

As the total of the remaining spaces (11 is inversely proportional to the thickness of sliver (W), the relation between (P,) and (W) can be represented by a curve wherein the abscissa represents the thickness of sliver (W) and the ordinate represents the pneumatic pressure (P,), as are shown in FIGS. 4A, 4B and 4C. As can be clearly seen each curve has an inflection point where the sensitivity is maximum. Therefore, to attain best results, the values of (P and (W) must be set about this inflection point.

The infelction points can be theoritically found by well-known mathematical analysis, that is, from a solution of the second differential formed from equation (I) is calculated. Accordingly, the following solution is obtained,

LLL 1 Therefore, by substituting (2) into the Equation (1 the following relation between (P,) and (P is found to satisfy the best condition of sensitivity of the airmicrometer.

To find the best practical conditions of the airmicrometer, several standard samples were prepared, and relation between P,, and thickness of sliver was confirmed for several values of a and a The experimental results are shown in FIGS. 4A, 4B and 4C, wherein W represents the slivers thickness of approximately 25 g/m, W represents the slivers thickness of approximately 60 g/m.

From the diagrams shown in FIGS. 4A, 4B and 4C, the following conclusions can be made.

a. In the case of slivers thickness W if a 2.0 mm, any possible variation (V adjacent to W lies on the linear portion of the P -W curve except a, 4 mmtb. However ifa 1.5 mm or 1.0 mm, any possible variation V lies outside the linear portion of the P -W curve.

b. In the case of slivers thickness W if a, 1.0 mmdi, any possible variation (V of slivers thickness in a range which adjacent to W, lies in the linear portion of the P -W curve for each value of a from 4 mm to 6 mm. However, if a, 1.5 mmrb, the value a, 6 mm only satisfies a linear condition, and if a, 2.0 mm, no value of 0, applies.

c. For the three figures of different values of a,, it can be seen that as the diameter (a,) of the sliver passage of the delivery member 5b, becomes larger, the inclined angles of the linear portion of P,-W curves to .the ordinate become smaller, in other words, the larger the diameter of a, the more degraded is the sensitivity of the air-micrometer. However, if the diameter 0 is too small for the sliver delivered from the front rollers la,

lb, there is a certain possibility of separation when the sliver is taken by the callender rollers 6a, 6b.

(1. In any conditions (11,) it can be understood that the diameter (a,) of the sliver passage of the delivery member 5b is smaller, the sensitivity of the airmicrometer is more degraded.

e. There is a certain limitation of the pressure (P,) i satisfying the linear condition between P, and W. If, the pressure I is too small or too high, the linear relation between P, and W can not be attained so that the correct detection of the variation of slivers thickness can not be carried out. It was confirmed that the abovementioned limitation is in the range from 0.04 0.08

kg/cm f. According to the above-mentioned results, it is concluded that practical values of P and a are 0.04 0.08 kg/cm and 4.0 -0 6.0 mmrb respectively. Therefore, very reliable control can be attained by applying these condition to the automatic control system utilizing the air-micrometer of the present invention.

It must be noted that the application of the airmicrometer according to the present invention is not restricted to the automatic control system shown in FIG. 1, but also applicable to any other types of automatic control systems, for example Ever Even (re gistered trade mark, Automatic Control System of Daiwa Spinning Company Ltd.-, Japan), successfully.

What is claimed is:

1. In an automatic control system for controlling thickness of sliver delivered from a draft mechanism by a pair of callender rollers wherein said thickness of sliver is detected by an air-micrometer comprising a measuring device provided with a sliver passage, a conduit for supplying compressed air into said sliver passage, an orifice disposed in said conduit, a source for supplying said compressed air, and a mechanical means responsive to the back pressure created by said measuring device so that draft ratio of said draft mechanism is automatically regulated in accordance with an output of said mechanical means; an improvement of said air-micrometer provided with said measuring device comprising a delivery cylindrical member provided with an expanded hollow cylindrical spacev and a trumpet-like condenser provided with a funnel portion and a downstream hollow cylindrical end portion encircled by said expanded hollow cylindrical space of said delivery cylindrical member, said delivery cylindrical member provided with a hollow sliver passage formed at the downstream end portion thereof the upper end of said delivery member rigidly engaged with the downstream side of said funnel portion in alignment with the longitudinal axis of said downstream hollow cylindrical end portion and the axis of said sliver passage, an intervening space formed insaid hollow cylindrical space at a position between said downstream hollow cylindrical end portion of condenser and an inlet of said hollow sliver passage of said delivery member, and said hollow cylindrical space connected to said conduit.

4. An improved air-micrometer according to claim 2, wherein said expanded hollow cylindrical space of said delivery member is pressurized in a range between 0.04 0.08 kg/cm and the cross-sectional diameter of said sliver passageof said delivery member is chosen in the range between 4.0-6.0 mm. 

1. In an automatic control system for controlling thickness of sliver delivered from a draft mechanism by a pair of callender rollers wherein said thickness of sliver is detected by an airmicrometer comprising a measuring device provided with a sliver passage, a conduit for supplying compressed air into said sliver passage, an orifice disposed in said conduit, a source for supplying said compressed air, and a mechanical means responsive to the back pressure created by said measuring device so that draft ratio of said draft mechanism is automatically regulated in accordAnce with an output of said mechanical means; an improvement of said air-micrometer provided with said measuring device comprising a delivery cylindrical member provided with an expanded hollow cylindrical space and a trumpet-like condenser provided with a funnel portion and a downstream hollow cylindrical end portion encircled by said expanded hollow cylindrical space of said delivery cylindrical member, said delivery cylindrical member provided with a hollow sliver passage formed at the downstream end portion thereof, the upper end of said delivery member rigidly engaged with the downstream side of said funnel portion in alignment with the longitudinal axis of said downstream hollow cylindrical end portion and the axis of said sliver passage, an intervening space formed in said hollow cylindrical space at a position between said downstream hollow cylindrical end portion of condenser and an inlet of said hollow sliver passage of said delivery member, and said hollow cylindrical space connected to said conduit.
 2. An improved air-micrometer according to claim 1, wherein the diameter of aperture of said downstream hollow cylindrical end portion is smaller than the cross-sectional diameter of said sliver passage of said delivery cylindrical member.
 3. An improved air-micrometer according to claim 1, wherein said measuring device is positioned so as to satisfy a distance requirement between the termination of said funnel portion of said condenser and the nip point of said callender rollers, said distance being not more than twice the mean length of the fibers in said sliver.
 4. An improved air-micrometer according to claim 2, wherein said expanded hollow cylindrical space of said delivery member is pressurized in a range between 0.04 - 0.08 kg/cm2 and the cross-sectional diameter of said sliver passage of said delivery member is chosen in the range between 4.0-6.0 mm. 